Cancer, physical activity, and exercise

Abstract

This review examines the relationship between physical activity and cancer along the cancer continuum, and serves as a synthesis of systematic and meta-analytic reviews conducted to date. There exists a large body of epidemiologic evidence that conclude those who participate in higher levels of physical activity have a reduced likelihood of developing a variety of cancers compared to those who engage in lower levels of physical activity. Despite this observational evidence, the causal pathway underlying the association between participation in physical activity and cancer risk reduction remains unclear. Physical activity is also a useful adjunct to improve the deleterious sequelae experienced during cancer treatment. These deleterious sequelae may include fatigue, muscular weakness, deteriorated functional capacity, and many others. The benefits of physical activity during cancer treatment are similar to those experienced after treatment. Despite the growing volume of literature examining physical activity and cancer across the cancer continuum, a number of research gaps exist. There is little evidence on the safety of physical activity among all cancer survivors, as most trials have selectively recruited participants. The specific dose of exercise needed to optimize primary cancer prevention or symptom control during and after cancer treatment remains to be elucidated.

Figure 1

A paradigm of physical activity and cancer research.

Figure 2

A conceptual model to guide and organize the role of physical activity across the cancer control continuum. Reproduced with permission from (32).

Figure 3

Individual risk factor contributions to mortality from all cancers, worldwide. Data from (176).

Figure 4

Relative risk and 95% confidence intervals (95% CI) comparing highest versus lowest levels of physical activity and cancer risk reduction.

Figure 5

Candidate mechanistic pathways linking physical activity and breast cancer. Reproduced with permission from (165).

Figure 6

Strength of evidence linking physical activity and hypothesized cancer prevention mechanistic pathways.

Figure 7

Weight adjusted treatment effect ratio of exercise to control on sex hormone concentrations after 12-months. Data from (53).

Figure 8

Adjusted insulin sensitivity according to frequency of participation in vigorous intensity physical Activity. Data from (102).

Figure 9

Adjusted fasting glucose according to frequency of participation in vigorous intensity physical Activity. Data from (102).

Figure 10

Exercise intensity and optimal states of infection risk and immuno-surveillance. Reproduced with permission from (115).

Figure 11

Prevalence of upper limb dysfunction among breast cancer survivors. Data from (185).

Figure 12

Prevalence of congestive heart failure at varying doses of anthracyline. Data from (161).

Figure 13

Prevalence of any cardiac event at varying doses of anthracycline. Data from (161).

Figure 14

New comorbidities acquired post-transplant at 37-month follow-up. Data from (86).

Figure 15

Physiologic effects occurring as a result of exercise training during cancer treatment. Data from (154).

Figure 16

Psychosocial effects occurring as a result of exercise training during cancer treatment. Data from (35, 154).

Figure 17

The intersection of Cancer and Aging. Reproduced with permission from (137).

Figure 18

Breast cancer surveillance and rehabilitation model. Reproduced with permission from (64).